PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Regional model”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1989

[Possibility of modeling regional characteristics of the level and structure of morbidity and the utilization of medical services by the population].

The feasibility of modelling the annual level and the pattern of gerenal morbidity (applications for aid) of the population according to the data on a single application for aid during one month of the year was based on the established regularities of seasonal changes in patients' applications for aid. It was established that an average day level of applications for aid each month in relation to average annual levels was a constant value governed by the peculiarities of seasonal distribution and irrespective of the value of the intensive morbidity indicator in the region. Distribution of applications for medical aid by week days also appeared to be constant. Proceeding from the data on population's applications for aid during 2-4 days the proposed system of coefficients enabled one to obtain the necessary information on the regional character of population's morbidity and various health care needs, thus it became possible to assess adequacy of the level of medical services to the population's health care needs in this region and also to supply information on various analytical, managerial, and planned standard problems. Experimental examination of feasibility and reliability of the model development of the level and pattern of general morbidity on the basis of a single registration of regional consultation rates was tackled by means of computer-based registration of the morbidity of 25,000 residents of Kineshma, the Ivanov Region.

Health Services↗
PubMed1990

[The loose-leaf book of procedures. A regional model for diagnostic and referral routines--a basis for improved cooperation between primary and secondary services].

Initiated by the Telemark branch of the Norwegian Medical Association a loose-leaf book of procedures has been prepared for use in the region of Telemark Central Hospital. The professional advice given in the book is based on an agreement between the chief physicians of the various hospital units, their discussions in the unit, and a group of four general physicians. The advice is only intended as a guide. The editors' idea is to have the book distributed to all G.P.s and hospital units in Telemark. The book is meant to be updated once a year.

Community Health Services↗
PubMed1990

The Alberta Hereditary Diseases Program: a regional model for delivery of genetic services.

Genetic counselling and related services are generally provided at major university medical centres because they are very specialized. The need for rurally based genetic services prompted the inclusion of an outreached program in the Alberta Hereditary Diseases Program (AHDP), which was established in 1979; the AHDP was designed to provide services to the entire province through two regional centres and seven outreach clinics. There is a community health nurse in almost every health unit whose duties are either totally or partially devoted to the AHDP; thus, genetic help and information are as close as a rural health unit. The AHDP is designed to provide complete clinical (diagnostic, counselling and some management) services and laboratory (cytogenetic, biochemical and molecular) services for genetic disorders. In addition, the program emphasizes education and publishes a quarterly bulletin, which is sent free of charge to all physicians, hospitals, public health units, social service units, major radio and television stations, newspapers and public libraries and to selected individuals and groups in Alberta.

Alberta↗
PubMedDate not supplied

Regional pharmacokinetics. III. Modelling methods.

Regional pharmacokinetics is the study of drug concentrations in specific regions of the body due to drug uptake and elution. Mathematical methods of interpreting regional pharmacokinetic data can vary greatly in their complexity depending on their intended use (i.e. to describe or predict), but must reinforce rather than replace experimental pharmacokinetics. 'Black box' analysis provides and empirical method for the study of complex pharmacokinetic systems using either statistical moment or linear systems analysis. However, these methods are only applicable to linear and time-invariant systems, and ignore the large body of information concerning the physiological and physiochemical basis of regional pharmacokinetics. Clearance concepts are suitable for describing linear drug uptake processes, but mass balance principles have wider applications in describing the rate and extent of both drug uptake and elution. Compartmental models of a region can vary from single compartment descriptions based on the concept of venous equilibrium to complex multi-compartmental models of the intravascular, interstitial, and intracellular spaces, in which drug transport between compartments is a function of drug binding and ionization. Ultimately, as more regional pharmacokinetic information is obtained, more complex three dimensional models may be necessary such as those used to describe the uptake of oxygen from capillaries.

Animals↗
PubMed1988

A model for regional blood flow measurements during cardiopulmonary resuscitation in a swine model.

Recent reports examining regional blood flow during cardiopulmonary resuscitation (CPR) have been criticized for several reasons: (1) cardiac arrest times of 5 min or less are not reflective of the prehospital setting, (2) anesthetic agents may significantly influence autonomic control of regional blood flow, (3) canine cardiac anatomy and coronary blood supply are not reflective of humans and (4) precise validation data for blood flow measurements have not been reported. This study presents a methodology and model for measuring regional blood flow during CPR after a prolonged cardiac arrest. Fifteen swine weighing 15-25.4 kg were instrumented for regional blood flow measurements using tracer microspheres. Regional cerebral and myocardial blood flow were measured during normal sinus rhythm (NSR) and during CPR following a 10-min cardiopulmonary arrest. Regional blood flow (ml/min/100 g) to the cerebral cortices averaged less than 3% of baseline flow (NSR: right cortex = 41.2 +/- 13.8; left cortex = 41.2 +/- 12.2; CPR: right cortex = 1.3 +/- 1.2; left cortex = 1.3 +/- 1.3). Total myocardial blood flow averaged less than 5% of baseline flow (NSR = 211.5 +/- 104.9; CPR = 9.5 +/- 14.9). The flow data demonstrates minimal cardiac and cerebral perfusion with standard CPR following a 10-min arrest. The variability in the pilot data may be used in determining sample sizes for future studies.

Animals↗
PubMedDate not supplied

Investigation of a new murine model of regional lymph node metastasis: characteristics of the model and applications.

The RC tumor, originally a renal adenocarcinoma very sensitive to different classes of chemotherapeutic agents, maintained in CDF 1 mice, was examined for its ability to metastasize. When inoculated into the foot (with 10(7) tumor cells), bulky metastases developed in the popliteal and para-aortic lymph nodes, in a constant and reproducible pattern, producing a massive microscopic invasion of the liver, the lungs and the spleen. The antigenicity tests demonstrated a low immunogenicity of the tumor. Chemotherapy assays showed that adriamycin and vincristine were effective against metastatic dissemination when administered early after tumor cell inoculation and principally when combined with excision of the tumor-bearing leg. The RC model appears to be suitable for the study of lymph node metastasis and could be used in chemotherapy trials of new drugs potentially effective against metastases of the lymphatic system.

Adenocarcinoma↗
PubMed1991

Comparison and critique of two models for regional drug delivery.

A simple stochastic recirculatory formalism is used to compare models of regional drug delivery due to Hunt et al. and Boddy and Aarons. It is shown that these two models are equivalent when regional delivery is ideal. The latter model has the advantage of simplicity. However, the former model appears more useful in relating predictions to experimentally accessible quantities. Neither model is sufficiently general to cover all possible topologies of regions associated with drug response and toxicity. Knowledge of this topology is essential in determining the drug targeting index. The underlying assumptions of the models are discussed, and situations where these assumptions may break down are identified. Finally, it is noted that the analysis of regional delivery may also apply to metabolite and prodrug kinetics.

Drug Administration Schedule↗
PubMed1991

Myocardial cytoprotective efficacy of azapropazone in a swine model of regional myocardial ischemia/reperfusion injury.

The purpose of the present study is to determine the myocardial cytoprotective efficacy of azapropazone (AZA) on regional myocardial function in anesthetized swine model of regional myocardial ischemia/reperfusion injury. AZA was administered (100 mg/kg, i.v.) 15 minutes prior to reflow. The left anterior descending (LAD) coronary artery occlusion was maintained for a total of 30 minutes and then reperfused for 120 minutes. The effects of AZA on regional segmental shortening (% SS) as well as on neutrophil migration were examined in the (proximal) central and border (distal) zones within the area at risk (AAR). AZA reduced the incidence of myocardial fibrillation which occurred in some animals during the LAD occlusion/reperfusion periods. AZA produced a significant recovery of left ventricular segmental shortening (% SS) in the border, but not in the central zones within the AAR. No significant differences in the hemodynamic parameters were observed between the AZA (n = 14) and the saline-treated (n = 17) groups. AZA produced a significant inhibition of neutrophil migration (as evident from the decrease in myeloperoxidase activity) into epi- and endocardium central and border zones within the AAR. It is concluded that AZA may elicit its cardioprotection in moderately but not in severely injured myocardium by inhibiting the neutrophil migration.

Animals↗
PubMed1988

Pharmacokinetics of methotrexate during regional hyperthermia in a pig model.

In the pig model, regional hyperthermia in the gluteus was combined with the infusion of 150 mg MTX over a period of 100-120 min. The pharmacokinetic data reveal that this approach is capable of simulating the situation that is necessary and achievable in medium-dose MTX therapy of human tumours. Under MTX infusion, serum levels in the region of 10(-5) M are attained. As an expression of a renal and hepatic MTX excretion, high levels of MTX are found both in the urine and in the bile. Especially high concentrations of MTX are found in the liver and kidney tissue. In the normothermic and hyperthermic muscle, very low MTX levels are found. The pharmacokinetic data obtained show that the selected model is suitable for the future investigation of the effect of regional hyperthermia and MTX on transplanted tumours.

Animals↗
PubMed1986

The rabbit as an experimental model for regional chemotherapy. 1. Intra-arterial hindlimb infusion.

Regional delivery of chemotherapy to a tumour or tumour-bearing region has pharmacokinetic advantages over the systemic route. The applications of an animal model for regional drug delivery are outlined. The technique for intra-arterial infusion in the rabbit hindlimb is described. The use of the implantable VX2 rabbit carcinoma as a model for solid human tumours may be studied by this method. Pharmacokinetic data obtained with the model allow comparison between systemic and regional routes of delivery. The distribution of the cancerostatic plant toxin ricin following regional delivery has been investigated using this experimental model.

Animals↗
PubMed1987

The importance of limited exposure to ultraviolet radiation and dietary factors in the aetiology of Asian rickets: a risk-factor model.

Regional variation in the prevalence of Asian rickets was examined in Coventry, Bradford and Glasgow. Records of 152 weeks of daylight outdoor exposure were obtained from 104 Glasgow Asian children, 53 of whom had been treated for rickets. Records of seven-day weighed dietary intake were obtained from 84 Asian children, 43 of whom had been treated for rickets. There was a marked north-south gradient in the prevalence of Asian rickets. In all cases of severe rickets with deformity the child was vegetarian. Severe rickets was associated with lower intake of meat, higher intake of chapati and lower daylight outdoor exposure values than in normal children. Multivariate analysis employing a combination of these variables provided good separation between rachitic and normal groups. A risk-factor model is proposed which suggests that regional variation in the prevalence of rickets among Asian communities in Britain is mainly determined by the effects of latitude and the nature of the urban environment on available ultraviolet radiation. Where UV radiation is restricted, individual propensity to rickets within a given Asian community is mainly determined by dietary factors.

Adolescent↗
PubMed1989

Occupational health in the Negev: a model for regional planning.

In the Negev region of Israel, I tested a model approach to occupational health planning. This model included components assessing exposures, measuring adverse health outcomes, and evaluating health services. I analyzed employment survey data, compiled an exposure data base, and carried out site visits covering 10,707 employees (over 50% of the regional industrial work force). Site visits identified exposure hazards of inorganic and organic dusts, heavy metals, chemicals, pesticides, and noise. I identified elevated relative regional injury rates by Standard Morbidity Ratios (SMRs) in a variety of industries, including sixfold increases for mining and non-metallic minerals manufacture (SMR 6.8, 99% CI 6.1-7.7). Review of biological monitoring data suggested deficiencies in pesticide and heavy metals surveillance. A survey of primary care clinics estimated 13,707 cases of occupational injury and illness untreated by existing occupational medical services. Based on these findings, I formulated regional occupational health planning goals, including targeting high-risk industries for increased preventive activities. This regional approach, combining multiple measures of occupational health status, can serve as a model for assessing local public health planning needs.

Agriculture↗
PubMed1991

Maintenance of multiallelic polymorphism at the MHC region.

Models that purport to explain the maintenance of MHC polymorphism must be able to explain a variety of phenomena. (1) The range of MHC allele frequencies at some of the loci is very large, with some alleles quite common and many others rare, while at others the range of allele frequencies is far narrower. (2) MHC alleles and their frequencies often have long persistence times, in some cases tens of millions of years. (3) Random-mating populations appear to be in Hardy-Weinberg equilibrium for MHC. (4) There is no obvious, strong and consistent selection pressure yet detected that acts differentially on different MHC genotypes. (5) Because the allelic composition of the MHC polymorphism does change over evolutionary time, the MHC system must be capable of accommodating new alleles with similar properties without destruction of the equilibria that permit the maintenance of the older alleles. In this review I examined the degree to which a large number of models that have been proposed fit these criteria. These include heterosis, marginal overdominance, conditional heterosis, assortative mating, maternal-fetal incompatibility, molecular mimicry, minority advantage, pathogen adaptation, and optimum allele frequency models. Most of the models do poorly at accounting for a number of the above phenomena. The last class, optimum allele frequency models, have the most satisfactory set of properties. However, optimum allele frequency models require mechanisms that somehow "feed back" from the frequency of an allele in the population to the fitness of an organism carrying that allele. Thus, these models require that MHC polymorphisms be maintained by some type of group selection. Evidence for an against optimum allele frequency selection, and ways in which this type of selection might be detected experimentally, are presented.

Alleles↗
PubMedDate not supplied

Detection with echo-planar MR imaging of transit of susceptibility contrast medium in a rat model of regional brain ischemia.

Gradient-refocused echo-planar magnetic resonance (MR) images (TE = 18 msec) were acquired in rats during bolus injection of iron oxide particles, and the first pass of the contrast agent through the brain was monitored. In control rats, contrast agent (0.1 mmol/kg iron) produced significant signal-intensity (SI) reduction over the right hemisphere and similar declines over the left. SI loss occurred first in the cortex and basal ganglia and later in the periventricular regions, along the midline, and in the thalamic zone. Sequential volume-localized proton spectra acquired during transit of 0.02 mmol/kg iron showed substantial reduction in SI, slight asymmetric broadening, and no change in chemical shift of the water resonance. In rats with unilateral occlusion of the middle cerebral artery, peak reduction in ischemic brain SI was to 70% +/- 9% of control, while normal brain SI was reduced to 18% +/- 2% (P less than .01), allowing distinction of the ischemic regions. The presence and location of injury were confirmed with diffusion-weighted imaging and postmortem vital staining. These results demonstrate abnormal transit profiles in a rat model of regional brain ischemia. Evaluation of dynamic contrast delivery patterns may provide unique information in early brain ischemia.

Animals↗
PubMed1977

A theoretical model of regionally ischemic myocardium.

The isometric tension development of a one-dimensional regionally ischemic muscle was analyzed theoretically. The model consist of a one-dimensional normal segment in series with a one-dimensional ischemic segment. Each segment is modeled as a three-element muscle. The inputs to the various elements, except the contractile element in ischemic segment, were obtained from published data for cat papillary muscles. To be consistent with segment length measurements on ischemic canine hearts, it was assumed that the ischemic contractile element contracted normally at the beginning of contraction and then at some tension, TM, fell behind in its rate of tension development compared to the contractile element in the normal segment. Rate of tension development of various lengths of the ischemic segment and strengths of the ischemic contractile element. At the tension, TM, the ischemic segment begins undergoing paradoxical expansion and, simultaneously, as a result of the expansion. the time derivative of the tension produced by the regionally ischemic muscle exhibits a sudden decrease.

Animals↗